This invention relates to a stuffing box seal to provide a sealing action between a stationary wall of a housing and a shaft. Such as seal is known, see the U.S. Pat. No. 3,659,862.
As is known such stuffing box seals consist of soft packing rings, which are arranged between the shaft and the respective wall of the housing or with a fixed component connected therewith in an annular space and which are sealingly urged against both the shaft and the respective housing wall by the gland. However, it frequently occurs that the shaft does not run true but slightly off center. Even if such eccentricity only amounts to 0.2 to 0.3 mm the result will be the exceedingly rapid development of a leak and intolerable losses of liquid from the space which is to be sealed off. This eccentricity of the shaft will in fact cause a widening of the stuffing box packing in the radial direction. Such eccentric running of the shaft may be entailed by imbalance or inaccuracy in manufacture or frequently however, by loads of the shaft during operation. In order to prevent radial spread of the packing of the stuffing box in the case of conventional stuffing boxes the gland has to be frequently tightened up in order to reduce the stuffing box clearance to zero again. Thus, naturally the working life of the stuffing box is substantially curtailed.
The German patent 711,850 has proposed lengthening the life of a stuffing box packing by providing an axial abutment surface for the stuffing box packing in the form of a shaft collar. This led to a certain improvement, more particularly in combination with compression springs.
Similar designs, which utilize the described principle of an axial abutment surface with a soft annular seal are described in the British patent 644,017, the British patent, 1,111,615, the Belgian patent 564,493, the French patent 403,498, and the Russian patent 918,607.
All these numerous designs in accordance with the prior art for seals based on the use of soft sealing material serve to indicate that industry has a considerable and acutely felt need for a seal with a long working life but that so far the simple solution provided by the present invention has not yet been discovered.